How do you respond to a complaint about the electricity bill?

First, check the overview of the property and the period: it shows exactly when the guest purchased credit, how much, and how consumption was distributed across the days. Structure your response in three steps: acknowledge that an unexpected amount feels frustrating, show the facts from the overview, and only then explain how the kWh price led to that amount. Refer to the overview that the guest could already see during their stay, so you remind rather than assert. If the complaint is about communication beforehand or about the property itself, that is a different conversation than a calculation error.